Wavelength division multiplexing (WDM) has enabled telecommunication service providers to fully exploit the transmission capacity of optical fibers in their core network. State of the art systems in long-haul networks now have aggregated capacities of terabits per second. Moreover, by providing multiple independent multi-gigabit channels, WDM technologies offer service providers with a straight forward way to build networks and expand networks to support multiple clients with different requirements. At the same time these technologies have evolved down through the local area networks to the subscriber access networks and into data centers to support the continuing inexorable demand for data. In order to reduce costs, enhance network flexibility, reduce spares, and provide reconfigurability many service providers have migrated away from fixed wavelength transmitters, receivers, and transceivers, to wavelength tunable transmitters, receivers, and transceivers as well as wavelength dependent add-drop multiplexer, space switches etc.
At the same time, improvements in imaging technology have had a great impact on modern medicine. Imaging is a powerful tool that allows non-invasive diagnostics, helps to plan and direct surgical interventions, and facilitates treatment monitoring. One emerging imaging techniques is Optical Coherence Tomography (OCT), which can provide high-resolution 3D images. This technique is a non-invasive and non-contact technology. In the last decade, optical coherence tomography has found applications in several medical fields, including ophthalmology, dermatology, cardiology, dentistry, neurology, and gastroenterology.
At first sight, the provisioning of wavelength tunable transmitters, receivers, and transceivers for optical telecommunications may seem to have little in common with medical imaging systems operating at video frame rates with cycling speed rates of over 1 kHz and delay ranges of more than 3.33 ps to support millimeter depth penetration using OCT. However, in both applications the requirements for smaller footprint, improved performance, and reduced cost have led to the adoption of monolithic optical circuit technologies, hybrid optoelectronic integration, and exploitation of technologies such as microelectromechanical systems (MEMS).
A common MEMS element to both is a MEMS mirror capable of deflection under electronic control. However, unlike most MEMS device configurations where the MEMS is used to simply switch between two positions in these devices the state of MEMS is important in all transition positions. Additionally, in the optical system designs described according to embodiments of the invention the MEMS mirror rotates in-plane. The characteristics of the MEMS determines the characteristics of the whole optical delay line system and by that the OCT system in one and in the other the number of wavelength channels and the dynamic wavelength switching capabilities in the other. The role of the MEMS is essential and it is responsible for altering the paths of the different wavelengths in either device.
Accordingly, it would be beneficial to improve the performance of such MEMS and thereby the performance of the optical components and optical systems they form part of. Beneficially, the inventors have established a range of improvements to the design and implementation of such MEMS mirrors as well as optical waveguide technologies supporting the extension of these device concepts in the mid-infrared for optical spectroscopy for example.
Other aspects and features of the present invention will become apparent to those ordinarily skilled in the art upon review of the following description of specific embodiments of the invention in conjunction with the accompanying figures.